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Výnosometr

Effective from 30/09/2026

Privacy policy

What data Výnosometr processes, why, for how long and what your rights are. The calculator works without an account and without cookies.

In short:

  • You can use the calculator without an account. Your inputs then stay only in your browser.
  • With an account we process your e-mail (with Google sign-in also your name and profile picture) and the calculations you save.
  • We use no advertising or cross-site tracking cookies and never sell data. Anonymous visit statistics run only with your consent.
  • You can delete your account and all saved data at any time in the app.

1. Controller

The controller is Michal Smetana, company ID (IČO) 87769620, business address Pobřežní 29/48, 186 00 Praha 8 - Karlín ("operator", "we"). Privacy contact: kontakt@vynosometr.cz. We have not appointed a data protection officer as the law does not require one. The Czech version of this policy is authoritative.

2. Data, purposes, legal bases and retention

  • Account data (e-mail; with Google also name, picture and Google account ID; language; sign-up and last sign-in dates): to run your account, send sign-in links and service notices. Contract, Art. 6(1)(b) GDPR. Kept until you delete the account, at most 24 months after your last sign-in (with prior notice).
  • Saved properties and calculations (names, city, notes, listing links, inputs): to store and reopen them. Contract, Art. 6(1)(b). Kept until you delete them or the account.
  • Technical logs (IP address, browser, time and URL of the request, sign-in events): security, abuse prevention and troubleshooting. Legitimate interest in a secure, working service, Art. 6(1)(f). Server logs 3 days, sign-in logs 1 day.
  • Visit statistics (Cloudflare Web Analytics: page viewed, referrer, browser and device type, country, page load speed): to learn which parts of the site are used. Consent, Art. 6(1)(a); runs only after you consent. We see aggregate figures only.
  • Calculator usage events (which field changed, mode switches, button use, result colour; no amounts, no link to your account, a random ID valid only while the page is open): to learn what is clear and improve the calculator. Consent, Art. 6(1)(a); nothing is sent with Do Not Track or Global Privacy Control on. Kept for at most 24 months.
  • Error reports (error text, code location, page without parameters, app version, browser and OS family such as "Chrome 140 / macOS"; no inputs, no cookies, no link to your account; nothing is sent with Do Not Track or Global Privacy Control on): to find and fix bugs. Legitimate interest in a working service, Art. 6(1)(f). Kept for 90 days.
  • Feedback form answers (Tally), optionally your e-mail: to improve the calculator and, if you leave an e-mail, to arrange a call. Legitimate interest, Art. 6(1)(f); for the e-mail your consent, Art. 6(1)(a), which you may withdraw at any time. Answers kept for at most 24 months, the e-mail until the call is arranged and at most 6 months.
  • E-mail correspondence: to answer your message or request. Legitimate interest, Art. 6(1)(f); for GDPR requests legal obligation, Art. 6(1)(c). Kept while handled and then at most 3 years for possible claims.

An e-mail address is required to create an account; without it you cannot save calculations but can still use the calculator. With Google sign-in we receive from Google only your name, e-mail, profile picture and account ID. Please do not enter data about other people in names or notes. There is no automated decision-making or profiling under Art. 22 GDPR; the traffic-light rating is a calculation on your numbers, not an assessment of you.

We use no advertising or tracking cookies. The browser's local storage keeps only what the service needs: your current calculation, language, currency, EUR rate, colour theme, your consent choice and, once signed in, your session. This is strictly necessary storage under Section 89(3) of Czech Act No. 127/2005 Coll. and needs no consent.

Visit statistics and calculator usage events run only with your consent, because the measuring scripts read information from your browser. You choose in the banner on your first visit and can change your choice at any time below or via Consent settings in the footer. Declining does not limit the calculator in any way.

Our network (Cloudflare) may set a technical cookie used only to tell people from bots. The Share link feature puts your inputs into the link after the # sign; that part is never sent to our server, but anyone you send the link to will see all your inputs.

4. Who processes the data

  • Supabase, Inc. (USA): database and authentication, including usage events; stored in the EU (Frankfurt), remote access from the USA possible; standard contractual clauses.
  • Cloudflare, Inc. (USA): hosting, content delivery, security, server logs, visit statistics (with consent), forwarding of mail to kontakt@vynosometr.cz; EU-US Data Privacy Framework and standard contractual clauses.
  • Tally BV (Belgium, EU): feedback form embedded on the Feedback page; when you open that page it processes technical data (IP address, browser), your answers only if you submit the form; data stays in the EU.
  • Plus Five Five, Inc., operator of Resend (USA): sending sign-in e-mails; Data Privacy Framework and standard contractual clauses.
  • Google Ireland Limited: mailbox (Gmail) receiving mail sent to kontakt@vynosometr.cz; Data Privacy Framework and standard contractual clauses.

If you sign in with Google, Google Ireland Limited also processes the sign-in data as an independent controller under its privacy policy. We share data with public authorities only where the law requires it. We fetch the EUR rate from the Czech National Bank via our server without sending any of your data.

5. Your rights

You have the right of access, rectification, erasure (delete your account in the app under My properties), restriction, portability (we send your data as JSON on request), the right to withdraw consent at any time as easily as you gave it, and the right to lodge a complaint with the Czech Office for Personal Data Protection, Pplk. Sochora 27, 170 00 Praha 7 (uoou.gov.cz).

Right to object (Art. 21 GDPR). You may object at any time to processing based on legitimate interest (technical logs, error reports, feedback, correspondence) on grounds relating to your situation. We will stop unless we demonstrate compelling legitimate grounds or need the data for legal claims.

Write to kontakt@vynosometr.cz, ideally from your account e-mail. We reply within one month; in complex cases this may be extended by two months and we will tell you.

6. Deletion, security, age and changes

Deleting your account removes it and your calculations from the database immediately; access records in providers' logs expire within the periods above. Traffic is encrypted (HTTPS), each user can access only their own data, and there are no passwords. We will inform you of any breach posing a high risk to you. The service is intended for people over 18. We update this policy when processing changes; the current version and its effective date are always here and we announce material changes in advance by e-mail or in the app.